Ok people, lets stop and have a talk. Assume that this thing runs 100 people to Mars on a trip lasting 80 days.
Assume each person is 200 pounds. People weighing less than that we can assume bring personal gear with them to meet that number. Most male astronauts, at least in the US, weight in the 190-230 range female astronauts will weigh about 3/4 that on average. Let's use 200 to keep what is about to be rough math simple.
The weight of the people, not the food, water, spacecraft, only the people will be 20,000 pounds. That is about the weight of a current large satellite. That is 10 tons. Next item.
Water. Every human on this ship will need roughly 1.5 gallons of water a day. In space, due to calcium loss in zero G, you need even more water to prevent kidney stones. But let's keep the math low-ball and simple. The water needed for 100 people on an 80 day, one-way trip to mars is 12,000 gallons. 1 Gallon of water is 8.36 pounds, meaning that the water for this crew, AND ONLY THE WATER will weigh in with a mass of 100,320 pounds. The cargo limit of the US Space Shuttle, as an aside, was 60,000 max weight to LEO. So what is the volume of this water? Roughly speaking, a spherical container of radius 16.5 feet (diamater of 33 feet or almost exactly 11 meters) will hold this water. That was a lot smaller than I was expecting.
Now, we have a total mass to orbit of 120,000 pounds, or about the lifting capability of the Saturn V rocket. We have not talked tanks, air, food, the weight of the airframe itself, the weight of the fuel, engines anything. Humans need roughly 3-4 pounds of food a day, or 32,000 pounds for our crew here. Cut that in 1/2 due to dehydration etc as you won't take that with you; you will use the water. so 16,000 in food alone, not counting packaging, storage, refrigeration, cooking etc.
In the end double this for the space craft itself. Now you are talking about a payload in the 250,000 pound range. That is double the to orbit mass of a Falcon 9 Heavy.
And there are some design oddities here that make me raise an eyebrow. Why reusable to the surface of mars, and not something that you end up keeping in the mars environment. An Aldrin Cycler makes more sense to save every bit of mass you can.
Yet... he build a space program. He built the Falcon 9. He returned a booster to land to reuse. He is supplying the ISS. Musk has a history of overpromising, so let's take a step back from the train to hypeville and get a few Falcon Heavy cargos in orbit first. The dragon to Mars mission needs to happen, a lunar landing needs to happen, then I will start to get on the hype train.
But man, his art team is on-fucking-point, ain't it?
Edit to fix numbers cause IRsmrt